Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F232/00—Copolymers of cyclic compounds containing no unsaturated aliphatic radicals in a side chain, and having one or more carbon-to-carbon double bonds in a carbocyclic ring system
  • C08F232/08—Copolymers of cyclic compounds containing no unsaturated aliphatic radicals in a side chain, and having one or more carbon-to-carbon double bonds in a carbocyclic ring system having condensed rings

Definitions

• the present invention relates to compositions containing polycyclic olefins which polymerize under free-radical conditions to generate crosslinked polymers and copolymers.
• the invention relates particularly to polycyclic olefins which primarily contain bicycloheptenyl unsaturation units.
• Cyclic olefin copolymers possess a unique combination of properties such as low density, low moisture absorption, low birefringence, high transparency, and high strength.
• materials can also be produced having a wide range of glass transition temperatures. As a result, these materials are being tested for use in diverse applications such as electronics, CD-ROM disks, optical lenses, barrier films, and medical appliances.
• polycyclic olefin monomers A particularly attractive characteristic displayed by polycyclic olefin monomers is the ability to polymerize via a variety of reaction mechanisms. It is well-known that polycyclic olefins can be polymerized and/or copolymerized free-radically, cationically, or coordinatively using organometallic catalysts. Due to this mechanistic flexibility, a wide variety of functionalized comonomers can be incorporated into the cyclic olefin copolymer, which provides further control over the bulk properties of the material.
• polycyclic olefin monomers have the ability to polymerize free-radically, these monomers have been explored as potential candidates for use in free-radical cured thermosetting compositions. Indeed, polycyclic olefins have been shown to readily copolymerize with electron deficient olefins. Thermosetting resins incorporating polycyclic olefins can be expected to have many desirable properties, such as high Tg, hydrophobicity, and low shrinkage upon cure.
• the polycyclic olefin in order to obtain these desirable properties in a thermoset resin, the polycyclic olefin must be of a certain minimum molecular weight (i.e., the volatility of the olefin should be low) and must be sufficiently reactive with the propagating free radicals during cure to produce a highly crosslinked thermoset network.
• thermosets incorporating polycyclic olefins are only produced when the polycyclic olefin has low volatilty and contains little, if any, cyclopentenyl unsaturation.
• thermosets having a unique combination of beneficial properties.
• free-radically polymerizable compositions comprising polycyclic olefins, wherein the polycyclic olefins contain little, if any, cyclopentenyl unsaturation.
• these olefins are sufficiently reactive with the propagating free-radicals during cure to provide a highly crosslinked thermoset resin.
• invention compositions comprise high molecular weight polycyclic olefins having low volatility. Accordingly, the undesirable weight loss upon cure observed with many thermosetting compositions is considerably reduced.
• compositions comprising functionalized polycyclic olefin monomers.
• functionalized olefin monomers provide additional benefits such as increased adhesion to a variety of surfaces as well as greater control over glass transition temperatures.
• polycyclic olefin monomers contemplated for use in the practice of the present invention have the following structures:
• X is an optional bridging group
• Y is a maleimide, a substituted maleimide, an epoxy group, an oxazoline, a cyanate ester-substituted aryl, or an oxazine, and
• X is an alkylene or oxyalkylene comprising up to about 20 atoms, or X is a siloxane, and Y is an optionally substituted maleimide or oxazine. In a particularly preferred embodiment, Y is a benzoxazine.
• polycyclic olefin monomers contemplated for use in the practice of the present invention have the following structure:
• R, x, and n are as defined above, and
• Q is a bridging group selected from siloxane
• R′ is an alkylene, an arylene or a polycyclic hydrocarbyl.
• Q is a tetramethyldisiloxane.
• R is hydrogen or lower alkyl
• saturated straight chain alkyl or branched chain alkyl optionally containing optionally substituted aryl moieties as substituents on said alkyl chain or as part of the backbone of said alkyl chain, and wherein said alkyl chains have up to about 20 carbon atoms,
• each Ar is a monosubstituted, disubstituted or trisubstituted aromatic or heteroaromatic ring having in the range of 3 up to 10 carbon atoms, and Z is:
• each R is independently as defined above, r falls in the range of 1 up to 10, s falls in the range of 1 up to 10, and q falls in the range of 1 up to 50,
• each R is independently as defined above, t falls in the range of 2 up to 10, u falls in the range of 2 up to 10, and Ar is as defined above,
• each R is independently as defined above, and wherein each of r, s and q are as defined above,
• n 1, 2, or 3.
• the maleimide is N-methylmaleimide, N-ethymaleimide, N-propylmaleimide, N-butylmaleimide, N-t-butylmaleimide, N-hexylmaeimide, N-2-ethylhexylmaleimide, N-cyclohexylmaleimide, N-octylmaleimide, N-decylmaleimide, N-dodecylmaleimide, N-phenylmaleimide, 2-methyl-N-phenylmaleimide, 4-methyl-N-phenylmaleimide, 2-ethyl-N-phenylmaleimide, 4-ethyl-N-phenylmaleimide, 2,6-diethyl-N-phenylmaleimide, and the like, or a mixture of any two or more thereof.
• Succinimides contemplated for use in the practice of the present invention as component (B) have the following structure:
• each Q′ is independently a lower alkyl or fluorinated lower alkyl
• saturated straight chain alkyl or branched chain alkyl optionally containing optionally substituted aryl moieties as substituents on said alkyl chain or as part of the backbone of said alkyl chain, and wherein said alkyl species have up to 20 carbon atoms,
• each Ar is an optionally substituted nobornyl, a disubstituted or trisubstituted aromatic or heteroaromatic ring having in the range of 3 up to 10 carbon atoms, and Z is:
• each R′ is independently as defined above, r falls in the range of 1 up to 10, s falls in the range of 1 up to 10, and q falls in the range of 1 up to 50,
• each R′ is independently as defined above, t falls in the range of 2 up to 10, u falls in the range of 2 up to 10, and Ar is as defined above
• each R′ is independently as defined above, and wherein each of r, s and q are as defined above,
• each x is independently 0, 1 or 2
• Free-radical curing co-monomers contemplated for use in the practice of the present invention include electron poor olefins such as, for example, unsaturated anhydrides, (meth)acrylates, styrenes, cyanate esters, vinyl esters, divinyl compounds, and the like.
• anhydrides contemplated for use in the practice of the present invention include maleic anhydride, citraconic anhydride, itaconic anhydride, and the like, or Diels-Alder adducts of maleic anhydride, citraconic anhydride, itaconic anhydride, and the like, and cyclopentadiene.
• Diels-Alder adducts contemplated for use in the practice of the present invention have the following structure:
• each Q is independently an alkyl or substituted alkyl, each x is independently 0, 1 or 2, and m ⁇ 9.
• Divinyl compounds contemplated for use in the practice of the present invention are present such that there is no greater than one equivalent of divinyl compound plus said polycyclic olefin per equivalent of bismaleimide.
• the divinyl compounds have the following structure:
• each R a is independently hydrogen, lower alkyl or aryl
• each Q is independently —O—,—O—C(O)—,—C(O)— or—C(O)O—,
• saturated straight chain alkylene or branched chain alkylene optionally containing saturated cyclic moieties as substituents on said alkylene chain or as part of the backbone of the alkylene chain, wherein said alkylene species have at least 6 carbon atoms,
• each R is independently as defined above, Ar is as defined above, and each of t and u are as defined above,
• each R is independently as defined above, and wherein each of r, s and q are as defined above,
• (4) is derived from a dimer amine, and includes —(CH 2 ) 9 —CH(C 8 H 17 )—CH(C 8 H 17 )—(CH 2 ) 9 —,
• Curing catalysts contemplated for use in the practice of the present invention include free-radical initiators such as peroxy esters, peroxy carbonates, hydroperoxides, alkylperoxides, arylperoxides, azo compounds, and the like.
• thermoset The incorporation of polycyclic olefin monomers into a free radical curing thermoset imparts many useful properties to the final crosslinked material. It has been observed that these monomers increase the glass transition temperature of the thermoset while decreasing the coefficient of thermal expansion. Additionally, thermosets which contain polycyclic olefins have increased toughness versus those without these monomers. A further desirable benefit which can be attributed to these monomers when incorporated into a thermoset is low shrinkage upon cure. All of these properties are important in a variety of end use applications, such as for example optical disks, barrier films, medical appliances, and the like. In particular, the properties provided by these monomers are especially useful in semiconductor packaging applications such as, for example, die-attach adhesives. Invention compositions may be readily incorporated into die-attach formulations containing further components such as, for example, conductive fillers, to provide hydrophobic, low-shrinkage die-attach pastes.
• Polycyclic olefin monomers contemplated for use in the practice of the present invention contain at least one unit of bicycloheptenyl unsaturation and are readily synthesized via Diels-Alder chemistry, as shown below in Scheme 1.
• the temperatures required for this reaction to proceed are generally between 150 and 250° C. It is necessary to use an autoclave to conduct this reaction since all of the reactants have boiling points well below 100° C. Cyclopentadiene need not be used directly since this component of the reaction can be readily generated in situ from the retro Diels-Alder reaction of dicyclopentadiene. Both norbornene and norbornadiene are commercially available and convenient to use. Alternatively, these materials could also be generated in situ from ethylene or acetylene and cyclopentadiene, respectively, as shown in Scheme 2.
• R b H, Me, higher alkyl, Ar, CN
• the polycyclic olefin monomers described in Schemes 1-3 are all high molecular weight analogs of norbornene or norbornadiene. As such, their vapor pressure is extremely low, resulting in very little outgassing or weight loss during high temperature cure. It is of note that these high molecular weight species are sufficiently reactive with electron deficient monomers to produce highly crosslinked networks. Indeed, electron rich polycyclic olefins readily copolymerize free radically with a variety of electron poor olefins, to give alternating copolymers, as shown in Scheme 4.
• the polycyclic olefin monomers contemplated for use in the practice of the present invention can be copolymerized with a variety of electron deficient monomers to give a thermosetting composition which is sufficiently reactive to provide a highly crosslinked network. This reactivity can be extended to a variety of functionalized electron deficient olefins, resulting in thermoset resins with a wide range of attractive properties.
• invention compounds are particularly useful in the microelectronics industry, where properties such as hydrophobicity, ionic purity, low shrinkage upon cure, and the like, are extremely important. Indeed, formulations comprising invention compounds are attractive candidates for a variety of electronic packaging applications, such as, for example, die-attach pastes.
• the use of invention compounds in die-attach formulations provides die-attach pastes with high glass transition temperatures. This feature is particularly important since state of the art microprocessors generate more heat during operation than previous generations of microprocessors.
• invention compounds are also desirable in other microelectronic packaging applications, such as, for example, underfill, encapsulants, solder mask, and the like.
• the bicyclo[2.2.1 ]hepta-2,5-diene excess was stripped off in a rotary evaporator.
• the crude reaction product residue was then dissolved in 200 ml toluene and passed over a thin bed of silica gel.
• the toluene was then removed by rotary evaporation to yield a faintly yellow, low viscosity, liquid.
• the product was subjected to a nitrogen gas sparge at 60° C. for six hours to remove the last trace of volatiles.
• the final product was obtained in 96% yield, based on the initial 1,1,3,3-tetramethyldisiloxane limiting reagent used.
• the residue was dissolved in 200 ml toluene and passed over a thin layer of silica gel.
• the toluene was removed on a rotary evaporator and the residue was then sparged under nitrogen gas at 60° C. for several hours.
• the final product was obtained in 98% yield (based on the amount of 1,1,3,3-tetramethyldisiloxane originally charged).
• the product was an almost colorless, low viscosity liquid.
• thermoset compositions with a bismaleimide monomer, X-BMI, shown below,
• Mix A contained a miscible blend of X-BMI; 1,3-bis-bicyclo[2.2.1]hept-5-en-2-yl-1,1,3,3-tetramethyldisiloxane (“compound I”) and two percent by weight dicumyl peroxide.
• Mix B contained a miscible blend of X-BMI; 1,3-bis-(2-bicyclo[2.2.1]hept-5-en-2-yl-ethyl)-1,1,3,3-tetramethyldisiloxane (“compound II”), and two percent by weight dicumyl peroxide.
• a control mix was also made containing only X-BMI and two weight percent dicumyl peroxide.
• Example 3 The mixtures described in Example 3 were subjected to thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) experiments. Included in these tests were two additional mixtures containing compounds I and II, each catalyzed with two percent of dicumyl peroxide. These new mixtures were designated “mix C” and “mix D”, respectively.
• a third, additional mixture was made that contained X-BMI and 33.7% of 2-decyl-1-tetradecanol. The purpose of this last mixture was to have an additional control for weight loss and cure energy using a non-reactive diluent having a molecular weight intermediate between compounds I and II. This last mixture was designated “mix E”.
• TGA and DSC results for all of these mixtures and the control are shown in Table 2.
• Invention compositions were also tested for moisture uptake.
• Invention mixtures A and B were cured (200° C. for one hour) to give void free, cylindrical slugs that were approximately one centimeter in diameter and ranging between two and five centimeters in length. Similar slugs were prepared from the catalyzed BMI control mix. Three slugs from each group were included in a moisture up-take test. All of these slugs were placed in boiling deionized water for several hours. Initially, all of the samples had some weight loss, but this initial weight loss ceased after about 290 hours in the boiling water. This initial weight loss period was used to level all of the slugs by removing any residual water extractable components.

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• 2001
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